A device having a stack structure in which semiconductor chips are stacked as shown in FIGS. 7 and 8 (for example, see JP-A-2000-227439) is known as one of the capacitance type semiconductor sensors as described above, for example, as a semiconductor acceleration sensor for an air bag of a vehicle, for example. According to this device, a sensor chip 1 having an acceleration detector is adhesively mounted on a circuit chip 2 having a signal processing circuit and further the circuit chip 2 is adhesively secured in a package 3 formed of a ceramic substrate as shown in FIG. 8.
Furthermore, for example, four electrode pads formed at one side portion of the sensor chip 1 and electrode pads of the circuit chip 2 which are formed in connection with the four electrode pads of the sensor chip 1 are electrically connected to one another by bonding wires as shown in FIG. 7. Furthermore, the circuit chip 2 and the electrode leads 3a of the package 3 are also electrically connected to one another by bonding wires 5 (shown in FIG. 8).
The semiconductor acceleration sensor is fixed onto a print board by mounting the package 3 formed of the ceramic substrate on the print board. However, when deformation occurs in the print board, for example, deformation due to expansion/contraction caused by the surrounding temperature or deformation caused by an external impact or the like occurs in the print board, the stress corresponding to the deformation is transmitted to the package 3, and further transmitted to the circuit chip 2 or the sensor chip 1 adhering to the package 3. Such a stress breaks the adhesion between the circuit chip 2 and the sensor chip 1, causes breaking of the bonding wires 5, etc., and thus it is not favorable.
In view of the foregoing problem, the adhesion between the sensor chip 1 and the circuit 2 is carried out through elastic adhesion film 6 as shown in FIG. 8 so that no stress is transmitted from the circuit chip 2 to the sensor chip 1.
However, in the case of use of the elastic adhesive film 6, when vibration is transmitted from the external, it is confirmed that the sensor chip 1 on the adhesive film 6 resonates between the circuit chip 2 and the sensor chip 1. In such a case, the following problem occurs.
FIG. 9 shows a part of the sensor circuit formed on the sensor chip 1 and the circuit chip 2.
Capacitance 1a is formed of a movable electrode and a fixed electrode in the sensor chip 1, and the sensor chip 1 is provided with four electrode pads 1b. The four electrodes 1b comprise two input terminals, one output terminal and a ground terminal.
The circuit chip 2 is also provided with four electrode pads 2a, and the four electrode pads 2a comprise two output terminals, one input terminal and a ground terminal. The circuit chip 2 is provided with two carrier wave generators 2b for outputting carrier waves from the output terminals, and a conversion circuit 2c for converting a signal input from the input terminal to a voltage signal.
In the construction as described above, carrier waves which are voltages having opposite phases to each other are output from the two carrier wave generators 2b provided to the circuit chip 2 through the output terminals, whereby each carrier wave is input through the input terminal of the sensor chip 1 and the corresponding voltage is applied to the capacitance 1a. 
When an acceleration is applied and the movable electrode is displaced, the capacitance 1a is varied, and thus the signal corresponding to the variation of the capacitance 1a is output from the output terminal of the sensor chip 1. This signal corresponds to an acceleration detection signal, and it is input through the input terminal of the circuit chip 2 to the voltage conversion circuit 2c to be converted to a voltage signal in the voltage conversion circuit 2c. 
The acceleration detection is carried out by the acceleration sensor as described above. Therefore, the acceleration detection signal output from the output terminal of the sensor chip 1 is required to be accurately input to the input terminal of the circuit chip 2.
However, in the above conventional construction, the interval between the bonding wires 4 for electrically connecting the sensor chip 1 and the circuit chip 2 is relatively narrow, and thus the parasitic capacitance 7 occurring between the neighboring wires 4 is relatively large.
Therefore, the acceleration detection signal output from the output terminal of the sensor chip 1 is varied by the effect of the parasitic capacitance 7, and the sensor falls into a state where the acceleration detection signal is inaccurately input to the input terminal of the circuit chip 2. When the interval between the bonding wires 4 is varied by the resonance of the sensor chip 1 and the parasitic capacitance 7 is varied, the variation of the acceleration detection signal output from the output terminal of the sensor chip 1 by the effect of the parasitic capacitance 7 is also varied. Therefore, even when the zero-point of the output voltage (hereinafter referred to as “0-point output voltage) is determined with the acceleration detection signal of the sensor chip 1 for the acceleration of 0 as a standard, the 0-point output voltage is varied due to the variation of the interval between the bonding wires 4, and the accurate acceleration detection cannot be performed.